1. Field of the Invention
The present invention relates to a liquid crystal driving device having a channel selection function, and more particularly to a liquid crystal display in which channels of signals outputted from a digital signal receiver can be automatically selected according to frequencies of input signals, when the input signals are digital signals.
2. Description of the Prior Art
FIG. 1 is a block diagram showing a construction of a conventional liquid crystal display.
As shown in FIG. 1, the liquid crystal display includes a conversion board for receiving outside data and power supply, a LVDS section for converting the output of the conversion board into LVDS level and a LCD module for receiving the data and the power supply from the LVDS section through an input section. Herein, the conversion board includes a digital signal receiver (TMDS receiver) for receiving a digital signal, and a scaler for adjusting resolution. The LCD module includes a LCD panel, driving ICs, an inverter, a backlight, and a timing controller of outputting data signals, clock signals(dot signals) and various control signals for operating the driving ICs installed on the LCD panel.
In general, when an input data signal is a digital signal (DVI), a dot clock (signal) received together with the digital signal data is divided by 2 in the conversion board including the digital signal receiver (TMDS receiver) and the scaler, and then the 2-divided signals pass through two channels (even channel and odd channel: signal channels which are applied to even or odd drivers). Next, they are transmitted to the timing controller and the driving ICs through the LVDS section and the input section of the LCD module, and then data is finally displayed on the panel. Herein, a digital signal data applied to the LVDS section is equal to the digital signal data applied to the conversion board, and 2-divided signals applied to the LVDS section come out of the dot signal. However, in a case that the scaler is not included in the conversion board as shown in FIG. 2, in contrast with the above-described case in which the scaler is included in the conversion board as shown in FIG. 1, when the digital signal (DVI) is applied to the conversion board, full scaling can't be performed by only the digital signal receiver, but an image can be displayed on a central portion or a corner of the screen of the liquid crystal display.
However, in the case of a liquid crystal display without a scaler as shown in FIG. 2, when a dot signal carried with a digital signal as input signal is divided by 2 through two channels of the digital signal receiver, which are then applied to the timing controller and the driving ICs through the low voltage differential signal serial interface (LVDS section), the frequency of the two divided signals with a particular resolution may be sometimes lower than a minimum frequency for operating the timing controller or the driving ICs, thereby causing the display to be impossible.